Problem with the fridge

[marioxp]

The refrigerator is a Danfoss BD35F, it worked until last night, this morning the compressor does not turn on, it has been going on for hours. It gets electricity, I'm sure of that because I connected the fan after the thermostat and the relay, and the fan works.

The ship is in Greece, I thought it was because of the high temperature, but the compressor has not been working for hours, so the temperature in the storage has normalized.
Last year, the gas was topped up, but the service technician said that there was no shortage of gas, but rather a problem with the thermostat relay (the relay was replaced). I don't believe it's a lack of gas problem.

Does anyone have any idea what could be causing the compressor not to work?

[geoff]

try a new wire direct from the battery, the compressor takes a high initial load and the low voltage cut out reacts too fast to check with a multimeter Geoff

[Yngmar]

If you suspect the thermostat, just bridge the thermostat connectors and see if the compressor turns on, and/or measure the thermostat for continuity with a multimeter.

[sean c]

try a new wire direct from the battery, the compressor takes a high initial load and the low voltage cut out reacts too fast to check with a multimeter Geoff

I had a similar issue and it was was low voltage cutting out the fridge before it could get running. The previous owners changed fridges and the existing wires didn't reach so they added about 300mm of wire that was undersized. I was able to measure it with a multi meter at around 10v on start up which will trip the fridge to save your battery.
Sean

[marioxp]

If you suspect the thermostat, just bridge the thermostat connectors and see if the compressor turns on, and/or measure the thermostat for continuity with a multimeter.

I just added an electric thermostat so that the whole refrigerator gets electricity when the temperature rises above 6 C. The old mechanical thermostat is outside the refrigerator area and since the temperature is high it should be in the closed position, i.e. let electricity pass. Do I need to dismantle the mechanical thermometer? I guess I need to make a bridge between certain pins?

When I think about it, this problem occasionally occurs every summer, the rest of the year the fridge works fine with this setting.

This spring I installed an additional fan to ventilate the space where the compressor is located because I suspected the problem was that the compressor was not cooling down enough. This fan gets power as soon as the thermostat gives power to the refrigerator. It means that when the temperature in the refrigerator is below 6 C, neither the fan nor the refrigerator works, when the temperature rises, both the fan and the refrigerator get electricity. Now I noticed that the fan is working but the refrigerator is not.

[sean c]

Link to fault diagnostic guide.

https://penguinfrigo.co.uk/wp-content/themes/genesis-sample/pdf/3-Support-BD35-BD50-Fault-Diagnosis.pdf

[marioxp]

Link to fault diagnostic guide.

https://penguinfrigo.co.uk/wp-content/themes/genesis-sample/pdf/3-Support-BD35-BD50-Fault-Diagnosis.pdf

Thank you this is helpful!

[Yngmar]

If you suspect the thermostat, just bridge the thermostat connectors and see if the compressor turns on, and/or measure the thermostat for continuity with a multimeter.

I just added an electric thermostat so that the whole refrigerator gets electricity when the temperature rises above 6 C. The old mechanical thermostat is outside the refrigerator area and since the temperature is high it should be in the closed position, i.e. let electricity pass. Do I need to dismantle the mechanical thermometer? I guess I need to make a bridge between certain pins?

The thermostat normally goes between pin C and T on the fridge controller. If they're closed (connected), the compressor starts. That's where you'd normally also connect a replacement electronic thermostat.

The way you connected it, switching power to the compressor through the new thermostat, pins C and T should be bridged. The thermostat relay and wires need to be much larger because they carry the full compressor power instead. This also leads to early demise of the thermostat relay, which is now switching full power (contact burn) instead of just signal and most aren't designed for this.

So do check that a) pins C and T are closed (remove the old thermostat connected there) and b) sufficient voltage arrives at the compressor controller after going through your thermostat relay. It must be a minimum of 11.7V at the terminals to start.

[marioxp]

The thermostat normally goes between pin C and T on the fridge controller. If they're closed (connected), the compressor starts. That's where you'd normally also connect a replacement electronic thermostat.

The way you connected it, switching power to the compressor through the new thermostat, pins C and T should be bridged. The thermostat relay and wires need to be much larger because they carry the full compressor power instead. This also leads to early demise of the thermostat relay, which is now switching full power (contact burn) instead of just signal and most aren't designed for this.

So do check that a) pins C and T are closed (remove the old thermostat connected there) and b) sufficient voltage arrives at the compressor controller after going through your thermostat relay. It must be a minimum of 11.7V at the terminals to start.

Thank you Yngmar!

I made it unnecessarily complicated with an additional relay. Because I thought that high current does not pass through the electric thermostat, so I added a relay.

It turned out to be a problem with the voltage being too low, 9.9V

Now I have to find where the problem is, I believe that the problem is in some connection, I don't believe that the problem is in the wire itself, but that is also possible.

[captbrad]

I had a similar problem on my Vision 46. I contacted Isotherm and the tech told me to check voltage at the control unit with the power cables connected. While I had ~13v when disconnected, connected was only half that, indicating a short somewhere. I attempted to trace the line to locate the problem but that prove too difficult and time consuming. Instead, I wired a new circuit, bypassing the 301 panel, directly to the battery. Now it runs perfectly. On-Off controlled at the thermostat switch.